Transmission of scrub typhus to human volunteers by laboratory-reared chiggers.
Laboratory-reared, Rickettsia tsutsugamushi-infected Leptotrombidium arenicola and L. fletcheri chiggers were fed on 1 and 2 human volunteers respectively. All subjects developed typical clinical signs and symptoms of scrub typhus beginning days 8-10 post chigger attachment (PCA); these included fever, severe headache, myalgia, regional lymphadenopathy, and eschar. The two L. fletcheri subjects developed a transient generalized rash on days 3-4 after the onset of fever, and these two individuals also appeared to suffer a more severe clinical disease. Rickettsemias were detected in all three volunteers beginning on day 7 PCA, 1-3 days before the onset of clinical disease. Rises in indirect fluorescent antibody titers occurred starting on days 13-19 PCA (day 4-11 post fever) and in Weil-Felix OXK titers starting on days 26-22 PCA (days 7-14 post fever). These results strongly suggest that the use of laboratory-reared chiggers is a reliable means of transmitting scrub typhus infections to volunteers.
D000328:Adult; D000818:Animals; D000937:Antigen-Antibody Reactions; D006790:Host-Parasite Interactions; D006805:Human Experimentation; D006801:Humans; D008297:Male; D008875:Middle Aged; D008925:Mites / Q000472:pathogenicity*; D012285:Orientia tsutsugamushi / Q000276:immunology; D012612:Scrub Typhus / Q000635:transmission*; D014324:Trombiculidae / Q000472:pathogenicity*